Multiple myeloma (MM) is a life-threatening hematologic malignancy. Despite major advances, median survival is still only 5 years. Myeloma has a long clinically detectable premalignant phase called monoclonal gammopathy of undetermined significance (MGUS) that can be identified easily using the secreted biomarker monoclonal immunoglobulin (M protein). There is also an intermediate clinical stage referred to as smoldering multiple myeloma (SMM). SMM consists of approximately 50% of patients with MGUS who have clonal but nonmalignant disease and 50% of patients with early stage MM in whom the malignant transformation has occurred biologically but is not yet clinically apparent. Myeloma is unique among cancers because of the dramatic racial disparity in incidence; young blacks for example have a 3 fold higher risk of the disease than whites. Second, there is an increased incidence in close relatives that we have recently identified: first degree relatives hav a 2-3 fold higher risk of MGUS. Third, despite having an intermediate SMM stage that is ripe for early intervention, we are crippled in our ability to prevent myeloma since we are unable to discriminate malignant disease (MM) from clonal non malignant disease (MGUS) except through the presence or absence of clinical end-organ damage. Biomarkers that can reliably distinguish the two are critically needed. We have identified 3 fundamental questions that need to be answered: 1) When and why does MGUS originate? 2) What is the reason for the increased risk in blacks and in first degree relatives and what can it teach us about the etiology of the disease? 3) What are the specific biomarkers that can accurately identify SMM patients who have early malignancy and therefore destined to progress to symptomatic MM within 2 years? We have made major contributions to the understanding of MGUS, SMM, and MM and are well poised to address these 3 crucial questions. In Aim 1, we will determine for the first tim the onset and risk factors for MGUS by studying blood samples from 12,540 patients age 10-49 representing a stratified random sampling of the United States with overrepresentation of minorities. In Aim 2, we will study the incidence and risk factors for MGUS in first-degree relatives of patients with MM. In Aim 3, we will identify biomarkers that indicate the presence of malignant transformation in SMM, and thereby predict for imminent progression to symptomatic MM. We believe that our studies are highly innovative, and will have a far-reaching impact on our understanding of the etiology of MGUS, the reasons for the racial disparity and increased familial incidence, and provide biomarkers for early detection of malignancy. We also believe our results will fundamentally alter the early diagnosis and treatment of this disease.